Messages in this thread | | | From | David Woodhouse <> | Subject | Re: spin_lock forgets to clobber memory and other smp fixes [was Re: [patch] waitqueue optimization, 2.4.0-test7] | Date | Fri, 08 Sep 2000 11:03:14 +0100 |
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lk@tantalophile.demon.co.uk said: > I tried it with two compilers, one older than yours and one newer: > In both cases, the memory read occurs before "zzz".
andrea@suse.de said: > I guess Alexey point is that the current compiler doesn't notice > that.
I don't understand why we're bringing empirical evidence into this discussion. Didn't we get into the horrible mess we've already got w.r.t. compilers by relying on the existing behaviour never changing?
The GCC documentation exists. If it is unclear, file a bug, and/or obtain clarification from the developers or the C specifications.
Once that is done, code the kernel to that specification, without heed to the current _implementation_ of GCC.
Separately, you may wish to test that your particular version of GCC, on your architecture, with this phase of the moon, conforms to that specification. If it doesn't, file another bug.
Do not use the ambiguity of the specification as an excuse for coding to today's GCC implementation. We should have learned that lesson by now.
Please - come to a clear conclusion about the behaviour _permitted_ by the GCC documentation, and _then_ attempt to test it.
-- dwmw2
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